1. Field of the Invention
This invention relates to a movable camera apparatus, and particularly to a movable camera apparatus with a pan head in which a camera unit is driven in a pan (horizontal) direction and a tilt (vertical) direction so as to take a still picture or a motion picture.
2. Related Background Art
A movable camera apparatus of this kind according to the prior art, for example, is Japanese Utility Model Application Laid Open No. 6-9264, in which a camera unit is supported for tilt (vertical) rotation by a vertical support erected from a horizontal supporting portion, and a main circuit board is erected on the horizontal supporting portion so as to be opposite in position to a vertical supporting portion relative to the camera unit.
Another movable camera apparatus of this kind according to the prior art, for example, is Japanese Utility Model Publication No. 2-4319, in which two short vertical supporting portions are erected from a horizontal supporting portion and support a vertical (tilt) rotary shaft provided in the lowermost portion of a camera unit for vertical (tilt) rotation.
Pan rotation is designed so as to be effected with only a journalled rotary shaft.
Also, a portion (a worm portion, a drive motor, etc.) of a tilt drive unit is disposed in the horizontal supporting portion.
Further, the vertical (tilt) rotary shaft is hollow, and a cable for transmitting a signal from the camera unit is inserted therethrough and is directed to the fixed portion of a pan head. The way of leading it about is a simple one in which the cable is merely passed through an internal gap, but an opening portion is barely provided in a case member including a peripheral portion about which the cable is led, particularly the vertical support portion and the horizontal supporting portion near the root thereof.
According to the examples of the prior art as described above, the horizontal supporting portion supports the camera unit for vertical (tilt) rotation by an erected vertical supporting portion and, therefore, the load of the camera unit is concentrated in the tilt rotary shaft and bearing portion of the single vertical supporting portion. Thus, the surroundings of the tilt rotary shaft and the bearing portion must be mechanically strong and, as a result, the supporting portion becomes bulky and the entire apparatus becomes massive.
Also, since the main circuit board is erected on the horizontal support portion so as to be opposite in position to the vertical supporting portion relative to the camera unit, the weight of the horizontal (pan) supporting portion which is a movable portion is increased. Therefore, the acceleration or deceleration time becomes long and high-speed driving becomes impossible; alternatively, for effecting high-speed driving, a horizontal (pan) drive unit becomes bulky and the apparatus becomes massive.
Further, the two vertical supporting portions erected from the horizontal supporting portion are short. Therefore, the space for escape during vertical (tilt) movement of the camera unit is small, and the range of vertical (tilt) movement has to be limited narrowly so that a portion of the camera unit may not abut against the horizontal supporting portion.
Also, since the two vertical supporting portions are short, a vertical (tilt) drive unit cannot completely be contained in the supporting portion, but a portion of the vertical (tilt) drive unit leads into the horizontal supporting portion to thereby make the horizontal supporting portion correspondingly bulky, and space efficiency becomes bad.
Further, the vertical (tilt) rotary shaft provided in the lowermost portion of the camera unit is supported for vertical (tilt) rotation. Therefore, it will be apparent that the center of gravity of the camera unit is above the center of vertical (tilt) rotation. Therefore, the moment of inertia of vertical (tilt) rotation increases, and in order to obtain a necessary driving force, the vertical (tilt) drive unit becomes bulky and the apparatus becomes massive.
Further, since an opening portion is barely provided in the case member including the peripheral portion about which the cable is led, particularly the vertical supporting portion and the horizontal supporting portion near the root thereof, the working property when the cable from the camera unit is led about in the fixed portion is very bad.
The present invention has been made in view of the aspect as noted above, and an object thereof is to provide means for reducing the driving load to the drive unit of a camera of this kind to thereby make high-speed driving possible, and improving space efficiency to thereby enable a movable camera to be downsized and make the wide-range vertical (tilt) driving of a camera unit possible, and further improving the working property with which a connecting member from the camera unit to a fixed portion is led about.
It is a first object of the present invention to support the vicinity of the center of gravity of the camera unit from opposite sides thereof, to thereby achieve downsizing of the apparatus as a result of optimization of the driving force.
Further, it is a second object of the present invention to design a camera unit that does not abut against a horizontal supporting portion during vertical driving of the camera unit, to thereby widen the range of tilt driving of the camera unit.
Further, it is a third object of the present invention to connect a circuit board in the camera unit and a circuit board in a pan head together volutedly about a tilt shaft or a pan shaft by a flexible connecting member to thereby mitigate a rotational load for driving the camera unit.
Further objects and construction of the present invention will become apparent from the following description of an embodiment of the invention.